Vitamins
Evidence: strong_human
Pyridoxal-5-phosphate (P5P) is the active coenzyme form of vitamin B6, required by over 150 enzymes. Key roles: transamination and decarboxylation of amino acids, serving as a cofactor for aromatic L-amino acid decarboxylase (converting 5-HTP to serotonin and L-DOPA to dopamine), glutamic acid decarboxylase (producing GABA), cystathionine beta-synthase (homocysteine transsulfuration to cysteine), serine hydroxymethyltransferase (one-carbon folate metabolism), glycogen phosphorylase (glycogenolysis), and aminolevulinic acid synthase (heme synthesis).
Standard: 25-50mg P5P daily
Loading: 100mg/day for PMS or severe deficiency (short-term)
Maintenance: 25mg/day
Administration: oral
Timing: Morning with food. Often included in B-complex.
Duration: ongoing
The neuropathy risk is specifically from chronic high-dose pyridoxine (>200mg/day), not typically from P5P at standard doses. B6 is the critical cofactor for the neurotransmitter synthesis pathways — deficiency directly impairs serotonin, dopamine, and GABA production. Common in oral contraceptive users, alcoholics, and the elderly. Dream recall and vividness often increase with B6 supplementation. Magnesium and B6 are synergistic and often co-formulated for PMS, anxiety, and sleep.
P5P (pyridoxal-5-phosphate) is the bioactive form — avoids need for hepatic conversion from pyridoxine. Some individuals with liver dysfunction or genetic variants poorly convert pyridoxine to P5P. Brands: Thorne Pyridoxal 5-Phosphate, Pure Encapsulations P5P 50, Country Life P-5-P.
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